I had them on my Civic and the difference was amazing. I honestly refuse to see the problem assuming they are fitted correctly using levellers.
The problems are twofold:
One: The light source is a different shape to that of a filament lamp and therefore requires a completely different reflect. You MUST have automatic self levelling and headlamp washing system in place. Even retrofitting the correct enclosures and other bits you will still need to get the car inspected by VoSA before you can use it on the road.
On the Civic you were going even further into unchartered territory because the law says that the dipped beam MUST remain on whilst the main beam is in use. The Civic had H4s, you say so, the main and dipped cannot operate together.
Two: The Construction and Usage regulations make it patently clear that it's NOT lawful to use aftermarket HID conversions.
I'm still not sure that I prefer HIDs to a decent set of halogen lamps. I appreciate that the Civic had H4s and these types are always a compromise. Separate dip/main reflectors are far superior.
My concern is the lost acuity of vision from the artifical nature of the HID light. The human eye is much more acclimatised to natural light sources and filaments approximate this more closely than any gas discharge lamp.
Metal halide lamps do NOT produce a continuous spectra of radiaton. Filament lamps do.